6l2 (ESOPHAGEAL AND GASTRIC PLEXUSES. 



particles of food, irrespirable gases) enter the respiratory passages. Even the reflex act of cough- 

 ing, which, under ordinary circumstances, would get rid of the offending bodies, is abolished. 

 Thus, foreigu bodies may readily enter the lungs, and this is favoured by the fact that, owing to 

 the simultaneous paralysis of the oesophagus, the food remains in the latter for a time, and 

 may therefore easily enter the larynx. That this constitutes one important factor was proved 

 by Traube, who found that the pneumonia was prevented when he caused the animals to respire 

 by means of a tube inserted into the trachea through an aperture in the neck. If, on the con- 

 trary, only the motor recurrent nerves were divided and the oesophagus ligatured, so that in 

 the process of attempting to swallow, food must necessarily enter the respiratory passages, 

 "traumatic pneumonia" was the invariable result (Traube, 0. Frey). (b) A second factor 

 depends on the circumstance that, owing to the laboured and difficult respiration, the lungs 

 become surcharged with blood, because during the long time that the thorax is distended, the 

 pressure of the air within the lungs is abnormally low. This condition of congestion, or abnormal 

 tilling of the pulmonary vessels with blood, is followed by serous exudation (pulmonary oedema), 

 and even by exudation'of blood and the formation of pus in the air-vesicles (Frey). This same 

 circumstance favours the entrance of fluids through the glottis ( 352, b). The introduction 

 of a tracheal cannula will prevent the eutrance of fluids and the occurrence of inflammation. It 

 is probable that a partial paralysis of the pulmonary vaso-motor nerves may be concerned in the 

 inflammation, as this conduces to an engorgement of the pulmonary capillaries, (c) Lastly, 

 it is of consequence to determine whether trophic fibres are present in the vagus, which may 

 influence the normal condition of the pulmonary tissues. According to Michaelson, the 

 pneumonia which takes place immediately after section of the vagi occurs especially in the lower 

 and middle lol>es ; the pneumonia which follows section of the recurrents occurs more slowly, 

 and causes catarrhal inflammation, especially in the upper lobes. Rabbits, as a rule, die within 

 twenty-four hours, with all the symptoms of pneumonia ; when the above-mentioned precautions 

 are taken, they may live for several days. Dogs may live for a long time. If the 9th, 10th, and 

 12th nerves be torn out on one side in a rabbit, death takes place from pneumonia (Griinhagen). 

 In birds, bilateral section of the vagi is not followed by pneumonia (Blainville, Billroth), 

 because the upper larynx remains capable of closing firmly death takes place in eight to ten days 

 with the symptoms of inanition (Einbrodt, Zander, v. Anrep), while the heart undergoes fatty 

 degeneration (Eichhvrd), and so do the liver, stomach, and muscles (v. Anrep). According to 

 Wassilieff, the heart shows cloudy swelling and slight wax-like degeneration. Frogs, which at 

 every respiration open the glottis, and close it during the pause, die of asphyxia. Section of 

 the pulmonary branches has no injurious effect (Bidder). [Unilateral section of the vagus in 

 rabbits is followed within forty-eight hours by the appearance of yellowish-white spots on the 

 myocardium, especially near the interventricular septum, on the papillary muscles, and 

 along the furrows for the coronary arteries. The muscular fibres exhibit retrogressive changes, 

 whereby their striai disappear ; they become swollen up and filled with albuminous granules. 

 After eight to ten days, the interstitial tissue of these foci becomes infiltrated with small round 

 granular cells, especially near the blood-vessels. At a later stage, the interstitial connective- 

 tissue increases in amount, and the muscle atrophies. No effect is produced by section of 

 the depressor or sympathetic, and Fantino concludes that some of the fibres of the vagus exert a 

 trophic action on the myocardium.] 



9. The oesophageal plexus (fig. 434, r) is formed principally by branches 

 from the vagus above the inferior laryngeal, from the pulmonary plexus, and below 

 from the trunk itself. This plexus supplies the oesophagus with motor power 

 ( 156), the sensibility which is present only in the upper part, and it also supplies 

 fibres capable of exciting reflex actions. 



10. The gastric plexus (oo) consists of (a) the anterior (left) termination of 

 the vagus, which supplies fibres to the oesophagus and courses along the small 

 curvature, aud sends a few fibres through the portal fissure into the liver ; (b) the 

 posterior (right) vagus, after giving off a few fibres to the oesophagus, takes part in 

 the formation of the gastric plexus to which (c) sympathetic fibres are added at the 

 pylorus. Section of the vagi is followed by hyperemia of the gastric mucous 

 membrane (Panum, Pincus), but it does not interfere with digestion (Bidder and 

 Schjnidt), even when it is performed at the cardia (Kritzler, Schiff). 



11. About two-thirds of the right vagus on the stomach joins the cceliac 

 plexus, and from it branches accompany the arteries to the liver, spleen, pancreas, 

 duodeuum, kidney, and suprarenal capsules. The vagus supplies motor fibres to the 

 stomach, which belong to the root of the vagus itself and not to the accessorius 

 (Stilling, Bischoff). The gastric branches also contain afferent fibres, which, when 

 stimulated, cause reflexly a secretion of saliva ( 145). It is undetermined whether 



